BOX issues Area Forecast Discussion (AFD) at Aug 18, 10:43 AM EDT268
FXUS61 KBOX 181443
AFDBOX
Area Forecast Discussion
National Weather Service Boston/Norton MA
1043 AM EDT Sun Aug 18 2024
.SYNOPSIS...
Dangerous rip current continue due to distant Ernesto into
Monday. Low clouds will be slow to erode today due to persistent
onshore flow. A slow moving frontal system moving in from the
Great Lakes will bring several opportunities for showers and
thunderstorms through Tuesday. Localized downpours are possible,
but severe weather potential is very low. Drier weather for the
middle portion of the week with below normal temperatures.
Warming trend for Friday into next weekend, but with continued
generally dry weather.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
950 AM Update:
Made a few changes to the forecast based on observed trends and
latest near-term guidance.
Regarding PoPs/Wx, still kept the general idea that cloudy but
generally dry weather should exist most of the day for eastern
MA and much of RI. However ended up changing from probability
to areal coverage rain shower wording (e.g. isolated to
scattered showers) from Worcester County MA and western portions
of RI westward. For these locations, while it may not be
raining the whole day, the better chances for rains during the
daytime hrs are more focused for these locations. This is also
closer to the proximity of a southerly low level jet of around
25-30 kt drawing in enhanced moisture, which seems to be
responsible for this morning's rains in the region. For these
interior locations, it's a challenge to determine times when
there may be drier periods so felt carrying areal coverage
shower wording probably best describes expected conditions. I
did add a mention of heavy downpours in western MA and into the
western half of Hartford County based on radar trends in SW CT
where heavy rains have developed (see recent flood warnings in
New Haven and Fairfield Counties in SW CT). These rains will
spread northward through Hartford County into western MA, and
while persistent downpours could cause ponding and poor drainage
street flooding, not expecting this rain to rise to the level
of flash flooding.
Have also lowered temps by a few degrees with highs in the mid
70s; while some breaks in cloud cover seem possible later in
the day, mostly cloudy conditions should prevail and heating
should be very slow and gradual, with SE flow also keeping
coastal areas on the cooler end of that temperature range.
Previous discussion:
* Dangerous Rip Current Risk continues due to distant Ernesto.
Cyclonic flow in place with a trough parked over the Great Lakes
region. A shortwave trough will pass by this morning, with
another arriving late today. Still like the general idea from
the HRRR, but its precise location may not be all that good.
Thinking there should be a brief break from showers this
afternoon across RI and eastern MA.
Clouds will be slow to dissipate this morning, but should
eventually have some sunshine across just about all of southern
New England, but most sunshine should be across the eastern
half. These clouds should lead to below normal temperatures
region-wide, but perhaps slightly higher than what we had
Saturday.
Main concern along south-facing beaches continues to be the
high risk for rip currents due to the increased swell from
distant Ernesto.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM MONDAY/...
Highlights
* Dangerous Rip Current risk continues due to distant Ernesto.
* Showers along with isolated thunderstorms spread in from west
to east tonight into Mon.
Cyclonic flow lingers across the Great Lakes and New England
through this timeframe. The trough over the central/eastern
Great Lakes will slowly slide into the Mid Atlantic by early
Monday. Another shortwave lifts from the Mid Atlantic tonight.
A slow moving frontal system will gradually slide into Upstate
NY tonight as well. This will mean more widespread showers
during this time. Not out of the question there are some heavy
downpours given this environment, but think risk greater during
the day Monday, especially across interior southern New
England.
Above normal temperatures likely tonight due to the higher
dewpoints and clouds. Below normal high temperatures expected
Monday.
&&
.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
Highlights
* Cooler and unsettled Tuesday in the wake of a cold front
* High pressure builds over the region Wednesday with dry
seasonable weather persisting through the end of next week
* Trending warmer next weekend
Monday night into Tuesday
A cold front pushes through the region Monday night into
Tuesday. Residual moisture and a cold pool aloft may support
some lingering unsettled weather with the possibility of a few
showers into Tuesday morning. Thereafter we should dry out as
northwest winds usher in a cooler/drier air mass. 925 hPa temps
drop below 10 Celsius which will result in temperatures
consistent with early fall with highs topping out in the upper
60s to low 70s across southern New England on Tuesday.
Wednesday through Saturday
Skies clear Tuesday night into Wednesday as a drier air mass
characterized by PWATs around 0.5" settles over the northeast.
This will be followed by a large area of surface high pressure
that will support dry weather through next weekend. After the
cool/early fall like day on Tuesday, temperatures will gradually
rise through Saturday with highs in the upper 60s/low 70s
Wednesday afternoon rising to the low to mid 80s by Saturday.
Overall a seasonable and dry pattern mid to late next week.
&&
.AVIATION /15Z SUNDAY THROUGH THURSDAY/...
Forecast Confidence Levels:
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
15Z TAF Update:
Today: Moderate confidence.
IFR-MVFR ceilings to start; very slow improvement in low cloud
bases later this afternoon into the MVFR to borderline VFR
range. Best chance at rain showers from ORH-PVD westward and
visbys could be as low as 2 SM in heavier downpours, but visbys
in showers should more commonly lie in the 4-6 SM range. SE
winds 4-8 kt.
Today...Moderate confidence.
IFR stratus will slowly lift to MVFR with some spotty VFR as
onshore flow continues. Though we may mix enough across eastern
areas where we lift those lower ceilings more firmly to VFR.
Scattered morning showers across central and western areas. SE
winds 5-15 kts.
Tonight and Monday...Moderate confidence.
Return of IFR to LIFR stratus and fog with persistent onshore
flow. Showers and isolated thunderstorms spreading in from west
to east as the night progresses, then lingering through Monday.
E to SE winds around 5-10 kts or less.
KBOS TAF...High confidence in trends, moderate in exact timing.
IFR to start with decreasing -SHRA. Gradual improvement to MVFR
this afternoon, though it is becoming less likely that cloud
bases rise into VFR range. Ceilings deteriorate to IFR tonight
before another round of showers (some heavy at times?) overnight
into early Monday morning. SE winds 4-8 kt.
KBDL TAF...High confidence in trends, moderate in exact timing.
MVFR ceilings, with 3-6 SM -SHRA (TEMPO 2 SM visby SHRA thru
17z). Lighter SHRA for the afternoon to early evening before
another round of showers (some heavy at times?) overnight. Light
winds.
Outlook /Monday Night through Thursday/...
Monday Night: Mainly VFR, with local IFR possible. Chance SHRA,
isolated TSRA.
Tuesday: Mainly VFR, with local IFR possible. Chance SHRA.
Tuesday Night: VFR. Slight chance SHRA.
Wednesday through Thursday: VFR.
&&
.MARINE...
Forecaster Confidence Levels:
Low - less than 30 percent.
Medium - 30 to 60 percent.
High - greater than 60 percent.
Through Monday...High confidence.
Expecting persistent SE flow at 5-10 kts through the vast
majority of the period. Wind gusts remain generally below 20 kts
as well. Seas remain elevated due to the powerful swell
associated with Ernesto. This keeps 5-7 ft seas across the outer
waters through Monday. Small Craft Advisory continues through
Monday night across the outer coastal waters. This is also the
case for the nearshore waters across coastal Rhode Island where
3-5 ft seas linger through Monday. Rain showers along with a few
thunderstorms could spread into the waters tonight into Monday.
Outlook /Monday Night through Thursday/...
Monday Night through Tuesday: Winds less than 25 kt. Seas up to
5 ft. Chance of rain showers, isolated thunderstorms.
Tuesday Night: Winds less than 25 kt. Areas of seas approaching
5 ft. Slight chance of rain showers.
Wednesday: Winds less than 25 kt. Seas locally approaching
5 ft.
Wednesday Night through Thursday: Winds less than 25 kt.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...High Risk for Rip Currents through Monday evening for MAZ007-
022>024.
RI...High Risk for Rip Currents through Monday evening for RIZ008.
High Risk for Rip Currents through this evening for RIZ006-007.
MARINE...Small Craft Advisory until 8 PM EDT Monday for ANZ235-237.
Small Craft Advisory until 8 AM EDT Tuesday for ANZ250-254>256.
&&
$$
SYNOPSIS...Belk/RM
NEAR TERM...Belk/Loconto
SHORT TERM...Belk
LONG TERM...RM
AVIATION...Belk/Loconto/RM
MARINE...Belk/Loconto/RM
Source:
BOX issues Area Forecast Discussion (AFD) at Aug 18, 10:43 AM EDT----------------
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